Insect Growth Regulators

INSECT GROWTH REGULATORS
  • New category of insect control agents
  • Constitute a chemical group which do not kill a target but interfere with growth and development, act mainly on immature stages and not used in adult control

Based on mode of action

  • Chitin synthesis inhibitors(BPU)
  • Chitin inhibitors(Thiazine/ pyrimidine derivatives)
  • Juvenile hormone analogue(JHA)

Benzoylphenyl urea (BPU)

  • During each moult chitin is newly formed by polymerization of individual sugar molecules, this with proteins are  assembled into chains which in turn are assembled into microfibrils
  • Exact mode of action is not understood, it may be by interference with assembly of chitin chains into microfibrils
  • Immature insect stages exposed to there (BPUs) cannot complete ecdysis and die during moulting process
  • BPU also show a transovarial effect- exposed adult’s produce eggs in which the compound is incorporated into the egg nutrient
  • Egg development is normal but newly hatched larvae are incapable of hatching
  • BPU is effective against insects but not against ticks the  exception being Fluazuraon which is  active against ticks and mites
  • BPU is lipophilic, build up in body fat, released into blood stream, excreted unchanged
  • Diflubenzuron (Dimilin) is  lipophilic and renders12-14 weeks protection
  • Lufenuron(Program) - given orally, it accumulates in fat and is slowly released, flea takes it with blood and transfers it to eggs which are non viable within 24 hours of administration
  • Formation of larval chitin structure is blocked thus inhibiting  development of the larvae
  • Flufenoxyuron  is a Chitin synthesis inhibitor used against  blow flies
  • Triflumuron is used against lice / fleas

Chitin inhibitors(Thiazine/ pyrimidine derivatives)

  • Differs from BPU in chemical structure and mode of action -it alters deposition of chitin into cuticles
  • Cyromazine-larvadex-trazine derivative
  • Effective against blow flies,  house flies and mosquitoes
  • Larval moults to second and third instars affected when L1 comes into contact
  • Pour on preparation is effective for 13 weeks  after single pour on, dips/shower effect lasts longer
  • Dicyclanil is a pyrimidine derivative- when used on  diptean larvae as pour on formulation it gave  20 weeks protection. Used in  blow fly control

Juvenile hormone analogue(JHA)

  • Mimics activity of natural juvenile hormone and prevents metamorphosis to adults
  • Once the larvae is fully developed enzymes within the insect's circulating system, destroy the endogenous insect hormone permitting development to adult stage
  • The juvenile hormone analogue binds to the JH receptor site but because they are structured different, they are not destroyed by the insect estrases.
  • Hence metamorphosis and development to adult stage is impaired
  • Methoprene (altocid)- a terpenoid compound with low mammalian toxicity its sensitive to light and will not persist out doors
  • Used in indoor enviroinment as collars, shampoo, spray, dip and even feed as larvicide’s for horn fly control
  • Pyriproxyfen is used against fleas
  • Carbamate, fenoxycarb also acts as JHA
Last modified: Monday, 9 May 2011, 10:01 AM